let username2:string;
username2 = "xiaofei"

// 数组类型,定义数组的时候,必须声明数组内部存放数据类型
let user:number[] = [1,2,3]
let user2:string[] = ["xiaowang","xiaowang"]

// 语法2 
let covers:Array<string> = ["xiaowang"]

// 语法3:any代表任意的类型
let covers2:any = [1,2,3,"小王",{}]

// 枚举类型
enum state {
    error=0,
    success=1,
    timeout=2
}
const order = {
    id:100,
    date:"20211105",
    status:state.error
}

// 
let address:string | null;
address = null
// console.log(address);


// 
let subejct:object = {id:1}
let classes:object = []
let show:object = function(){}
let teacher:{} = {id:1,name:"xiaowang"}
let teacher2:{id:number,address:string} = {id:1,address:"xiaofei"}

export {}